Is 20 mg of tadalafil equivalent to 100 mg of sildenafil?

Not in any labelled or trial sense, and this page will not print that it is. Both figures are the maximum dose on their own label, and sildenafil's whole ladder — 25, 50 and 100 mg — happens to be exactly five times tadalafil's — 5, 10 and 20 mg. That is where the claim comes from: two dose ladders read across. The same reading makes tadalafil and vardenafil identical milligram for milligram, although one has a 17.5 hours half-life and the other approximately 4 to 5 hours, and it makes avanafil twice sildenafil rather than a fifth. No FDA label, guideline or trial states an equivalence between any two of the four.

What dose should I start on if I switch from one ED tablet to another?

The new drug's own labelled starting dose, and then titration from there with your prescriber. Those doses are 50 mg for sildenafil, 10 mg for tadalafil, 10 mg for vardenafil and 100 mg for avanafil. None of the four labels conditions its starting dose on what you were taking before — none of them mentions switching at all — so there is no adjusted figure to give you. The AUA guideline treats a change of agent as part of ordinary titration: "As part of the process of identifying the optimal dose, men may be offered dosing frequency changes or different PDE5i."

Is vardenafil more potent than sildenafil?

Two published pages answer that question and they are a factor of 2 apart. Medical News Today says "A 10-mg dose of vardenafil is approximately equivalent to 50 mg of sildenafil, or Viagra." — 5× — while Maximus says "Milligram-for-milligram, vardenafil is roughly 10x more potent than sildenafil, and tadalafil sits between them." — 10×. Neither cites a source. What the labels do state is selectivity for PDE5 over the retinal enzyme PDE6, and that is a comparison within each molecule rather than between them: about 10-fold for sildenafil, greater than 15-fold for vardenafil, greater than 100-fold for avanafil and 700-fold for tadalafil. A selectivity ratio is not a potency and a potency is not a dose.

Does taking a higher dose work better?

Much less than people expect, and this is the best-sourced number on the page. The AUA guideline reports: "The clinician should be aware that when PDE5i studies were examined in aggregate, the differences in response rates between dose groups were extremely small, rarely statistically significant, and generally not clinically significant." Its own worked example is sildenafil — average IIEF-EF after treatment was 22.6 on 50 mg and 23.8 on 100 mg, a gain of 1.2 points on a 30-point scale for doubling the dose. The guideline adds that this pattern "was consistent across the PDE5i", and that side-effect rates generally rose with dose. Its recommendation is to titrate to the dose that works for you, not to the highest one.

Can I take two different ED tablets together to get a stronger effect?

No, and all four labels say so independently. The sildenafil label: "The safety and efficacy of combinations of VIAGRA with other PDE5 Inhibitors, including REVATIO or other pulmonary arterial hypertension (PAH) treatments containing sildenafil, or other treatments for erectile dysfunction have not been studied. Such combinations may further lower blood pressure. Therefore, the use of such combinations is not recommended." The tadalafil label: "The safety and efficacy of combinations of CIALIS and other PDE5 inhibitors or treatments for erectile dysfunction have not been studied. Inform patients not to take CIALIS with other PDE5 inhibitors, including ADCIRCA." The avanafil label: "The safety and efficacy of combinations of STENDRA with other treatments for ED has not been studied. Therefore, the use of such combinations is not recommended." The vardenafil label carries the same position. A combination is not a way around the absence of an equivalence; it is an untested one with a blood-pressure risk attached.

Why will this page not just give me an approximate conversion?

Because an approximate figure with no source is indistinguishable, on the page, from a measured one — and a man who reads "tadalafil 20 = sildenafil 100" may start at the top of a ladder he should have started at the bottom of. The tadalafil starting dose is 10 mg, not 20 mg. Starting at 20 mg on the strength of an unsourced ratio skips the step where tolerability is assessed at a lower dose, and all four of these drugs lower blood pressure. The calculator on this page therefore has no conversion in it, and the tested module behind it has no function capable of performing one.

PDE5 Inhibitor Dose Equivalence

Why there is no PDE5 dose conversion, and what to use instead

No FDA label for any of the four PDE5 inhibitors states a dose equivalence with any other, and no published trial establishes one. Twenty milligrams of tadalafil is not "equal to" 100 mg of sildenafil in any labelled or trial sense. The only dose a label will give you for a drug is that drug's own. We looked: the four Structured Product Labels contain no mention of switching, prior PDE5 use or a converted dose anywhere in them; the AUA Erectile Dysfunction Guideline gives no equivalence; and no trial has ever been designed to establish one. What exists instead is four labels, each of which names a starting dose for its own drug and titrates from there.

The ratio everyone repeats is not a finding, and you can see exactly where it came from by lining the labelled ladders up. Sildenafil is 25, 50 and 100 mg. Tadalafil is 5, 10 and 20 mg. Vardenafil is 5, 10 and 20 mg. Sildenafil's rungs are exactly five times tadalafil's and exactly five times vardenafil's — at the bottom, in the middle and at the top. That is what "tadalafil 20 equals sildenafil 100" is: two dose ladders read across, by people who then described the reading as a potency. It is three companies choosing round numbers.

Two things fall out of that reading immediately, and both are fatal to it. It makes tadalafil and vardenafil 1 : 1 at every rung — 10 mg of one "equal to" 10 mg of the other — while their own labels put terminal half-lives at 17.5 hours and approximately 4 to 5 hours, and one has a licensed once-daily regimen while the other has none. And avanafil, whose ladder is 50, 100 and 200 mg, is 1 : 2 against sildenafil rather than a fifth. No circulating equivalence table includes avanafil. That is not an oversight; it is the rule failing in public.

The claims also disagree with each other, which is the quickest way to see that none of them is measured. Medical News Today states: “A 10-mg dose of vardenafil is approximately equivalent to 50 mg of sildenafil, or Viagra. This is because the chemical composition of vardenafil is different from that of sildenafil.” Maximus states: “Milligram-for-milligram, vardenafil is roughly 10x more potent than sildenafil, and tadalafil sits between them.” Those are 5× and 10× — a factor of 2 apart — for the same drug against the same comparator. Neither page cites a source for its number.

There is a further reason a conversion would matter less than it looks, and it comes from the guideline rather than from us. The AUA's recommendation on dose is simply: “For men who are prescribed PDE5i, the dose should be titrated to provide optimal efficacy. (Strong Recommendation; Evidence Level: Grade B)” In the discussion behind that statement it reports: “The clinician should be aware that when PDE5i studies were examined in aggregate, the differences in response rates between dose groups were extremely small, rarely statistically significant, and generally not clinically significant.” Its worked example is sildenafil: 50 mg took the average IIEF-EF score to 22.6, and 100 mg took it to 23.8. Doubling the dose of one drug is worth 1.2 points on a 30-point scale, and the guideline adds that “This pattern in which large dose increases (i.e., doubling the dose) resulted in small differences in average response level or rate was consistent across the PDE5i”. A precise milligram mapping between drugs would be answering a question whose answer barely moves.

The closest thing to a head-to-head comparison is ENDOTRIAL, which randomised men to four arms: “This was a spontaneous, open-label, randomized, multicenter, crossover study where the patients were randomized to receive sildenafil 50 mg, sildenafil 100 mg, tadalafil 20 mg, or vardenafil 20 mg.” Its conclusion was that “An overall equivalence was demonstrated in the subjective perception of treatment benefits for all the PDE5i tested.” Read that carefully, because it is the opposite of an equivalence table: 2 different sildenafil doses both came out equivalent to tadalafil 20 mg. If 50 mg and 100 mg of sildenafil are each "equal to" tadalafil 20 mg, no ratio can be extracted. The paper says the arms reflected “the common treatment regimens in real life”, not equipotent doses.

One last fact settles it. A 10 mg is not reliably a 10 mg even within one molecule: the vardenafil orally disintegrating tablet's own label states that it is “Vardenafil hydrochloride orally disintegrating tablets are not interchangeable with vardenafil 10 mg film-coated tablets (LEVITRA). Vardenafil hydrochloride orally disintegrating tablets provide higher systemic exposure compared to vardenafil 10 mg film-coated tablets (LEVITRA)”. Same drug, same number printed on the box, different systemic exposure, said by FDA. If two presentations of one molecule at one nominal strength are not interchangeable, a milligram mapping between four different molecules is not a thing that can exist.

So what do you do when you switch? Start at the new drug's own labelled starting dose and titrate from there, with your prescriber. That is the only instruction on any of the four labels, and the AUA treats a change of agent as part of the same titration process: “As part of the process of identifying the optimal dose, men may be offered dosing frequency changes or different PDE5i.” The tool above will tell you that dose, quote the sentence it comes from, and show you what really changes — the lead time, the duration basis, the food effect and the nitrate interval. It will not give you a converted number, because there is not one to give.

The formula

equivalent dose of drug B = (no such quantity is published)

What the labels support instead:

new dose = drug B’s own labelled starting dose

then = titrate up or down within drug B’s own range

sildenafil 25 → 50 → 100 mg

tadalafil 5 → 10 → 20 mg (or 2.5 → 5 mg once daily)

vardenafil 5 → 10 → 20 mg

avanafil 50 → 100 → 200 mg

The top line is not a joke and it is not a placeholder. No FDA label, guideline or trial defines that quantity, so this page has no expression for it and the module behind the page has no function that computes one. The ladders below are each label’s own, and the arrow means titration within a single drug on a prescriber’s advice — not a step you take yourself, and never a route from one ladder to another.

Worked example

A man on sildenafil 100 mg wants to know what dose of tadalafil that is. Worked through honestly:

Where is 100 mg on sildenafil's own ladder? It is the top rung — the label reads: “Based on effectiveness and toleration, the dose may be increased to a maximum recommended dose of 100 mg or decreased to 25 mg.” So he is at the maximum sildenafil supports, which is a real and useful thing to know.
What does the folklore say? Sildenafil's ladder is 5 : 1 against tadalafil's, so read across it gives tadalafil 20 mg. That number is arithmetic on two dose ladders and has no clinical source behind it.
What does the tadalafil label say? “The recommended starting dose of CIALIS for use as needed in most patients is 10 mg, taken prior to anticipated sexual activity.” — 10 mg, not 20 mg. The label states that starting dose flatly and does not condition it on what he was taking before, because it never mentions prior PDE5 use at all.
Titration from there is the label's own: “The dose may be increased to 20 mg or decreased to 5 mg, based on individual efficacy and tolerability.” So 20 mg may well be where he ends up. It is a destination reached by titration, not a starting point reached by conversion, and the difference matters because the second route skips the step where tolerability is assessed.
What actually changes: duration goes from up to 4 hours to up to 36 hours; the food effect goes from “A high-fat meal pushes the peak back a full hour and cuts it by 29% — the largest food effect of the four.” to “None. The label states absorption is not influenced by food at all.”; and the nitrate interval goes from “Label states none — "it is unknown"” to “At least 48 hours”. Those are the differences a conversion table hides.

What each label actually states — and nothing between them

Every figure here is from one drug’s own dosage section. There is deliberately no column relating one row to another, because no label, guideline or trial provides one.

Drug	Starting dosethe label’s own	Full rangeby titration	Maximum frequency	Once-daily option
avanafilStendra	100 mg	50 mg – 200 mg4-fold	Once per day	None on this label
sildenafilViagra	50 mg	25 mg – 100 mg4-fold	Once per day	None on this label
vardenafilLevitra	10 mg	5 mg – 20 mg4-fold	Once per day	None on this label
tadalafilCialis	10 mg	5 mg – 20 mg4-fold	Once per day	2.5 mg then 5 mg

This is the whole of what is sourceable about choosing a dose. The starting dose on each label is stated flatly and is not conditioned on anything — none of the four mentions prior PDE5 use, switching, or a converted dose, anywhere. No FDA label for any of the four PDE5 inhibitors states a dose equivalence with any other, and no published trial establishes one. Twenty milligrams of tadalafil is not "equal to" 100 mg of sildenafil in any labelled or trial sense. The only dose a label will give you for a drug is that drug's own.

Where the 5:1 ratio comes from — the ladders, read across

The three rungs of each label’s ED dose ladder, side by side, with the ratio to sildenafil’s. Read the last column before accepting any equivalence table.

Drug	Lowestby down-titration	Starting	Maximum	Ratio to sildenafilat every rung
avanafil	50 mg	100 mg	200 mg	1 : 2same at all three rungs
sildenafil	25 mg	50 mg	100 mg	Reference
vardenafil	5 mg	10 mg	20 mg	5 : 1same at all three rungs
tadalafil	5 mg	10 mg	20 mg	5 : 1same at all three rungs

Sildenafil's ladder is exactly five times tadalafil's and exactly five times vardenafil's, at every rung. That coincidence — three companies choosing round numbers — is the entire origin of the "tadalafil 20 = sildenafil 100" claim, and it is not a measurement of anything. Two things fall straight out of it. It makes tadalafil and vardenafil 1 : 1, while their labels put terminal half-lives at 17.5 hours and approximately 4 to 5 hours. And avanafil's ladder is 1 : 2 against sildenafil's — twice, not a fifth — which is why no circulating equivalence table includes avanafil at all.

What a ladder-derived equivalence would have to claim

Take the ratio between two labelled dose ladders seriously and these are the six statements it commits you to. Each is in the first column; what the labels say is in the second.

Pair	It would claim	But the labels say
sildenafil / tadalafil5 : 1	50 mg sildenafil = 10 mg tadalafil	Terminal half-lives are sildenafil about 4 hours, tadalafil 17.5 hours, and the labels state a food effect for one and no food effect for the other. Two drugs that clear the body at those rates are not interchangeable milligram for milligram.
sildenafil / vardenafil5 : 1	50 mg sildenafil = 10 mg vardenafil	Terminal half-lives are sildenafil about 4 hours, vardenafil approximately 4 to 5 hours. The ladders match because two companies chose the same round numbers, which is not a pharmacological finding.
tadalafil / vardenafil1 : 1	10 mg tadalafil = 10 mg vardenafil	Terminal half-lives are tadalafil 17.5 hours, vardenafil approximately 4 to 5 hours, and the labels state no food effect for one and a food effect for the other. Two drugs that clear the body at those rates are not interchangeable milligram for milligram.
avanafil / sildenafil2 : 1	100 mg avanafil = 50 mg sildenafil	Terminal half-lives are avanafil approximately 5 hours, sildenafil about 4 hours. The ladders match because two companies chose the same round numbers, which is not a pharmacological finding.
avanafil / tadalafil10 : 1	100 mg avanafil = 10 mg tadalafil	Terminal half-lives are avanafil approximately 5 hours, tadalafil 17.5 hours, and the labels state a food effect for one and no food effect for the other. Two drugs that clear the body at those rates are not interchangeable milligram for milligram.
avanafil / vardenafil10 : 1	100 mg avanafil = 10 mg vardenafil	Terminal half-lives are avanafil approximately 5 hours, vardenafil approximately 4 to 5 hours. The ladders match because two companies chose the same round numbers, which is not a pharmacological finding.

None of these six statements appears on any FDA label. They are what you get by doing the arithmetic everyone does silently, written out. A ratio that produces "10 mg tadalafil = 10 mg vardenafil" is not a ratio between pharmacological potencies; it is a ratio between two marketing departments’ preference for round numbers.

The equivalence table this page declines to print

Every specimen we could find of a published PDE5 dose equivalence, quoted exactly, with what its page cites in support. The last column is the same on every row.

The claim	As published	Cites	Status here
vardenafil 5× sildenafilMedical News Today	“A 10-mg dose of vardenafil is approximately equivalent to 50 mg of sildenafil, or Viagra. This is because the chemical composition of vardenafil is different from that of sildenafil.”	None given	Omittednot reproduced as fact anywhere on this page
vardenafil 10× sildenafilMaximus	“Milligram-for-milligram, vardenafil is roughly 10x more potent than sildenafil, and tadalafil sits between them.”	None given	Omittednot reproduced as fact anywhere on this page
tadalafil 5× sildenafilMaximus	“A 10mg tadalafil dose approximates a 50mg sildenafil dose in clinical effect.”	None given	Omittednot reproduced as fact anywhere on this page
Any ratio involving avanafilNobody	No specimen found	Not applicable	Omittedits ladder is twice sildenafil’s, which breaks the rule
A conversion this tool performsThis site	There is none, by construction	No source exists to cite	Refusedthe module behind this page has no conversion function and its test file forbids adding one

The two specimens about vardenafil disagree with each other by a factor of 2: Medical News Today puts it at 5× sildenafil and Maximus at 10×. On a number a man might use to decide what to swallow, two of the top-ranking answers are twice apart and neither cites anything. If you can point us to a primary source for any row here, this page will be updated to reflect it.

What actually changes when you switch — none of it a milligram

The honest answer to "what is the equivalent dose". Nothing converts; these four columns are what you are really choosing between.

Starting this drug	When to take it	How long it is documented for	Food	Nitrate intervalin an emergency
avanafilstarts at 100 mg	as early as 15 minutes beforedosage section instruction; 50 mg is 30 min, not 15	not statedhalf-life approximately 5 hr printed in its place	AffectedA high-fat meal delays the peak by about 1 hour; the label calls the change clinically minimal.	At least 12 hours
sildenafilstarts at 50 mg	approximately 1 hour beforedosage section instruction; 30 min to 4 hr permitted	up to 4 hourseffect documented to 4 hr, weaker than at 2 hr	AffectedA high-fat meal pushes the peak back a full hour and cuts it by 29% — the largest food effect of the four.	Label states none — "it is unknown"
vardenafilstarts at 10 mg	approximately 60 minutes beforedosage section instruction; no earlier time permitted	not statedhalf-life approximately 4 to 5 hr printed in its place	AffectedA high-fat meal cuts the peak by 18–50%. No delay to the peak is stated.	Label states none — "has not been determined"
tadalafilstarts at 10 mg	median 2 hr to peakno lead time on the label — this is Tmax, not onset	up to 36 hoursimproved erectile function vs placebo, not a 36 hr erection	No effect statedNone. The label states absorption is not influenced by food at all.	At least 48 hours

Switching means starting the new drug at the new drug’s own starting dose and titrating from there, because that is the only instruction its label contains. The AUA guideline treats a change of agent as part of the same titration process rather than as a conversion: “As part of the process of identifying the optimal dose, men may be offered dosing frequency changes or different PDE5i.” And all four labels are explicit that you do not take two at once — the safety and efficacy of combining PDE5 inhibitors have not been studied on any of them.

The only cross-drug figure all four labels state

Selectivity for PDE5 over PDE6, the retinal enzyme, quoted verbatim from section 12.1 of each label. It is the one number on the four labels that can be compared across them — and it is not a dose conversion.

Drug	PDE5 over PDE6label’s own wording	What it bears on	Implies a dose conversion?
avanafil	greater than 100-fold	Visual effects — PDE6 is in the retina	No
sildenafil	about 10-fold	Visual effects — PDE6 is in the retina	No
vardenafil	greater than 15-fold	Visual effects — PDE6 is in the retina	No
tadalafil	700-fold	Visual effects — PDE6 is in the retina	No

A selectivity ratio is a comparison between two enzymes within one molecule, not between two molecules. Tadalafil is 700-fold selective and sildenafil about 10-fold, and that tells you which is more likely to cause the blue-tinge visual effect — it tells you nothing about how many milligrams of one match how many of the other. Reading a selectivity figure as a potency ranking, and a potency ranking as a dose ratio, is the two-step error behind every equivalence table on the internet.

Frequently asked questions

Is 20 mg of tadalafil equivalent to 100 mg of sildenafil?: Not in any labelled or trial sense, and this page will not print that it is. Both figures are the maximum dose on their own label, and sildenafil's whole ladder — 25, 50 and 100 mg — happens to be exactly five times tadalafil's — 5, 10 and 20 mg. That is where the claim comes from: two dose ladders read across. The same reading makes tadalafil and vardenafil identical milligram for milligram, although one has a 17.5 hours half-life and the other approximately 4 to 5 hours, and it makes avanafil twice sildenafil rather than a fifth. No FDA label, guideline or trial states an equivalence between any two of the four.
What dose should I start on if I switch from one ED tablet to another?: The new drug's own labelled starting dose, and then titration from there with your prescriber. Those doses are 50 mg for sildenafil, 10 mg for tadalafil, 10 mg for vardenafil and 100 mg for avanafil. None of the four labels conditions its starting dose on what you were taking before — none of them mentions switching at all — so there is no adjusted figure to give you. The AUA guideline treats a change of agent as part of ordinary titration: "As part of the process of identifying the optimal dose, men may be offered dosing frequency changes or different PDE5i."
Is vardenafil more potent than sildenafil?: Two published pages answer that question and they are a factor of 2 apart. Medical News Today says "A 10-mg dose of vardenafil is approximately equivalent to 50 mg of sildenafil, or Viagra." — 5× — while Maximus says "Milligram-for-milligram, vardenafil is roughly 10x more potent than sildenafil, and tadalafil sits between them." — 10×. Neither cites a source. What the labels do state is selectivity for PDE5 over the retinal enzyme PDE6, and that is a comparison within each molecule rather than between them: about 10-fold for sildenafil, greater than 15-fold for vardenafil, greater than 100-fold for avanafil and 700-fold for tadalafil. A selectivity ratio is not a potency and a potency is not a dose.
Does taking a higher dose work better?: Much less than people expect, and this is the best-sourced number on the page. The AUA guideline reports: "The clinician should be aware that when PDE5i studies were examined in aggregate, the differences in response rates between dose groups were extremely small, rarely statistically significant, and generally not clinically significant." Its own worked example is sildenafil — average IIEF-EF after treatment was 22.6 on 50 mg and 23.8 on 100 mg, a gain of 1.2 points on a 30-point scale for doubling the dose. The guideline adds that this pattern "was consistent across the PDE5i", and that side-effect rates generally rose with dose. Its recommendation is to titrate to the dose that works for you, not to the highest one.
Has anyone actually compared the three head to head?: Once, and the result is why an equivalence table cannot be built even from it. ENDOTRIAL (PMID 19570039) randomised men to four arms: "This was a spontaneous, open-label, randomized, multicenter, crossover study where the patients were randomized to receive sildenafil 50 mg, sildenafil 100 mg, tadalafil 20 mg, or vardenafil 20 mg." It concluded that "An overall equivalence was demonstrated in the subjective perception of treatment benefits for all the PDE5i tested." But 2 of the four arms were different doses of sildenafil, so 50 mg and 100 mg both came out equivalent to tadalafil 20 mg. No ratio survives that. The trial also states its arms reflected "the common treatment regimens in real life" rather than doses chosen to be equipotent.
Can I take two different ED tablets together to get a stronger effect?: No, and all four labels say so independently. The sildenafil label: "The safety and efficacy of combinations of VIAGRA with other PDE5 Inhibitors, including REVATIO or other pulmonary arterial hypertension (PAH) treatments containing sildenafil, or other treatments for erectile dysfunction have not been studied. Such combinations may further lower blood pressure. Therefore, the use of such combinations is not recommended." The tadalafil label: "The safety and efficacy of combinations of CIALIS and other PDE5 inhibitors or treatments for erectile dysfunction have not been studied. Inform patients not to take CIALIS with other PDE5 inhibitors, including ADCIRCA." The avanafil label: "The safety and efficacy of combinations of STENDRA with other treatments for ED has not been studied. Therefore, the use of such combinations is not recommended." The vardenafil label carries the same position. A combination is not a way around the absence of an equivalence; it is an untested one with a blood-pressure risk attached.
Is 10 mg of one brand the same as 10 mg of another?: Not necessarily, even within a single molecule — which is the clearest possible demonstration that milligrams are not a common currency. The vardenafil orally disintegrating tablet and the vardenafil film-coated tablet are both labelled 10 mg, and the orally disintegrating label states: "Vardenafil hydrochloride orally disintegrating tablets are not interchangeable with vardenafil 10 mg film-coated tablets (LEVITRA). Vardenafil hydrochloride orally disintegrating tablets provide higher systemic exposure compared to vardenafil 10 mg film-coated tablets (LEVITRA)". Same drug, same number on the box, different exposure, and FDA requires the label to say so. If two presentations of one molecule at one strength are not interchangeable, a mapping between four different molecules is not a quantity that exists.
Why will this page not just give me an approximate conversion?: Because an approximate figure with no source is indistinguishable, on the page, from a measured one — and a man who reads "tadalafil 20 = sildenafil 100" may start at the top of a ladder he should have started at the bottom of. The tadalafil starting dose is 10 mg, not 20 mg. Starting at 20 mg on the strength of an unsourced ratio skips the step where tolerability is assessed at a lower dose, and all four of these drugs lower blood pressure. The calculator on this page therefore has no conversion in it, and the tested module behind it has no function capable of performing one.

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Next steps

The full side-by-side chartEvery labelled figure for all four, printable — onset basis, duration basis, alpha-blocker dose and nitrate interval, each with the sentence it came from.Compare online ED providersA switch needs a prescriber. These are the telehealth platforms that carry all four and what each one costs.